intelrdt: honor default closID

[giuseppe]

implement the change specified here:

opencontainers/runtime-spec#1289

Summary by Sourcery

Implement handling of the default CLOS ID per OCI runtime-spec: treat name '/' as the default clos, adjust file path resolution accordingly, and skip creation, validation, and destruction operations for it

Enhancements:

• Add is_default_clos and get_resctrl_path helpers to detect and build resctrl paths for the default CLOS ID
• Replace direct path concatenation with get_resctrl_path to handle default clos and normal clos uniformly
• Skip creation, validation, update, and destruction operations when the CLOS ID is the default '/'

[sourcery-ai]

Reviewer's Guide

This PR introduces special handling for the default Intel RDT CLOS ID (“/”) by adding helper functions to detect and build paths accordingly, and updates all rdt-related operations to skip unnecessary file-system interactions for the default CLOS.

Class diagram for updated Intel RDT CLOS handling

classDiagram
    class IntelRDT {
        +compare_rdt_configurations(a, b)
        +validate_rdt_configuration(name, l3_cache_schema, mem_bw_schema, err)
        +resctl_create(name, explicit_clos_id, created, l3_cache_schema, mem_bw_schema, err)
        +resctl_move_task_to(name, pid, err)
        +resctl_update(name, l3_cache_schema, mem_bw_schema, schemata, err)
        +resctl_destroy(name, err)
    }
    class get_resctrl_path {
        +get_resctrl_path(path, file, name, err)
    }
    class is_default_clos {
        +is_default_clos(name)
    }
    IntelRDT --> get_resctrl_path : uses
    IntelRDT --> is_default_clos : uses
    get_resctrl_path --> is_default_clos : calls

Loading

File-Level Changes

Change	Details	Files
Added helper functions for default CLOS detection and path building	Introduce is_default_clos(name) to check for “/” Implement get_resctrl_path() to route paths through default or named directories	src/libcrun/intelrdt.c
Replaced direct append_paths calls with get_resctrl_path	Use get_resctrl_path for SCHEMATA_FILE, TASKS_FILE, and base paths Remove redundant append_paths invocations	src/libcrun/intelrdt.c
Added default-CLOS-specific logic to skip ops	In resctl_create: treat default CLOS as existing, skip validation and Dir creation In resctl_destroy: return immediately for default CLOS	src/libcrun/intelrdt.c

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[sourcery-ai]

Hey there - I've reviewed your changes - here's some feedback:

• Extract the default CLOS ID string "/" into a named constant (e.g., DEFAULT_CLOS_ID) instead of hardcoding it in is_default_clos.
• Add a null or empty check for the name parameter in is_default_clos (or get_resctrl_path) to prevent potential null pointer dereferences.
• Include a brief code comment or link to the OCI runtime-spec PR explaining why the default CLOS ID is represented as "/".

Prompt for AI Agents

Please address the comments from this code review:
## Overall Comments
- Extract the default CLOS ID string "/" into a named constant (e.g., DEFAULT_CLOS_ID) instead of hardcoding it in is_default_clos.
- Add a null or empty check for the `name` parameter in is_default_clos (or get_resctrl_path) to prevent potential null pointer dereferences.
- Include a brief code comment or link to the OCI runtime-spec PR explaining why the default CLOS ID is represented as "/".

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[packit-as-a-service]

TMT tests failed. @containers/packit-build please check.

[giuseppe]

@kolyshkin @flouthoc PTAL

[kolyshkin]

lgtm